Conventionally, in a friction clutch device which is disposed between a prime mover and a driven body rotated and driven by the prime mover and which transmits drive force from the prime mover to the driven body or stops the transmission or in a brake device which brakes rotational motion provided by the prime mover, a flat, annular plate element is pressed against a flat, annular counterpart element, which is driven so as to rotate, so as to transfer rotational drive force between the plate element and the counterpart element, or so as to brake rotational motion of the counterpart element.
A plate element used in such a friction clutch device or brake device has a plurality of teeth radially projecting from the outer peripheral surface of a ring-shaped pressing element which is pressed against a clutch friction plate, as in the case of the clutch plate shown in below-mentioned Patent Document 1. The teeth formed on the outer peripheral surface of the plate element are engaged with recesses or grooves formed on the inner peripheral surface of an outer case which accommodates the plate element so that the plate element rotates as a single body with the outer case.